TRACY, Calif. — The Pentagon waited nine months after completing an investigation into the deaths of two U.S. soldiers before notifying relatives the men were killed by Iraqi troops, the military acknowledged Wednesday.

The June 2004 deaths of Army Spc. Patrick R. McCaffrey Sr., 34, of Tracy, and 2nd Lt. Andre D. Tyson, 33, of Riverside, were originally attributed to an ambush during a patrol near Balad, Iraq. The Army said this week a military investigation found the two had been shot by Iraqi civil defense officers. No possible motive has been divulged.

Military officials visited Tyson’s family on Tuesday and McCaffrey’s on Wednesday to deliver the report, which was completed on Sept. 30, 2005, according to Sen. Barbara Boxer, D-Calif. She called the nine-month delay troubling.

“If the American people knew that the people we are directly helping train turned on our soldiers, support for this war would slip,” Boxer said. “It’s very disturbing to think that the Pentagon might be told to keep this kind of thing close to the vest.”

“There was a time gap, no doubt about it,” Army spokesman Paul Boyce said. “The Army regrets any delay in notifying the family, and we took immediate steps to do so once those facts were determined.”

Soldiers who witnessed the attack have told Nadia McCaffrey two Iraqi patrolmen opened fire on her son’s unit. The witnesses also said a third gunman simultaneously drove up to the American unit in a van, climbed onto the vehicle and fired at the Americans, she said.